Abstract
The cryptochrome 1 (cry1) photoreceptor is responsible for the majority of the inhibitory effect of blue light on hypocotyl elongation, but phytochrome photoreceptors also contribute to the response through a phenomenon known as coaction. In Arabidopsis thaliana the participation of phytochromes A and B (phyA and phyB) in the early phase of cry1 action was investigated by determining the effects of phyA, phyB and hy1 mutations on a cry1-dependent membrane depolarization, which is caused by the activation of plasma-membrane anion channels within seconds of blue light treatment. High-resolution growth measurements were also performed to determine the timing of the requirement for phytochrome in cry1-mediated growth inhibition, which is causally linked to the preceding anion-channel activation. A null mutation in PHYA impaired the membrane depolarization and prevented the early cry1-dependent phase of growth inhibition as effectively and with the same time course as mutations in CRY1. Thus, phyA is necessary for cry1/cry2 to activate anion channels within the first few seconds of blue light and to suppress hypocotyl elongation for at least 120 min. This finding furthers the notion of an intimate mechanistic association between the cry and phy receptors in mediating light responses. The absence of phyB did not affect the depolarization or growth inhibition during this time frame. Instead, double mutant analyses showed that the phyB mutation suppressed the early growth phenotypes of both phyA and cry1 seedlings. This result is consistent with the emerging view that the prevailing growth rate of a stem is a compromise between light-dependent inhibitory and promotive influences. It appears that phyB opposes the cry1/phyA-mediated inhibition by promoting growth during at least the first 120 min of blue light treatment.
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Claims 7
Claim · model-written summary
A PHYA null mutation impaired cry1-dependent membrane depolarization.
- Taxon
- Arabidopsis thaliana
Arabidopsis thalianae1 - Treatment
- null mutation in PHYAe0
- Gene
- PHYAe0
- Outcome
- membrane depolarizatione0
- Direction
- impairede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A null mutation in PHYA impaired the membrane depolarization”
e1“In Arabidopsis thaliana”
Claim · model-written summary
A PHYA null mutation prevented the early cry1-dependent growth inhibition.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae1
- Treatment
- null mutation in PHYAe0
- Gene
- PHYAe0
- Outcome
- early cry1-dependent phase of growth inhibitione0
- Direction
- preventede0
- Comparator
- mutations in CRY1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A null mutation in PHYA impaired the membrane depolarization and prevented the early cry1-dependent phase of growth inhibition as effectively and with the same time course as mutations in CRY1”
e1“In Arabidopsis thaliana”
Claim · model-written summary
Absence of phyB did not affect early membrane depolarization.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae1
- Treatment
- absence of phyBe0
- Gene
- phyBe0
- Outcome
- depolarizatione0
- Direction
- did not affecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The absence of phyB did not affect the depolarization or growth inhibition during this time frame”
e1“In Arabidopsis thaliana”
Claim · model-written summary
Absence of phyB did not affect early growth inhibition.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae1
- Treatment
- absence of phyBe0
- Gene
- phyBe0
- Outcome
- growth inhibitione0
- Direction
- did not affecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The absence of phyB did not affect the depolarization or growth inhibition during this time frame”
e1“In Arabidopsis thaliana”
Claim · model-written summary
The phyB mutation suppressed early growth phenotypes of phyA seedlings.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae1
- Treatment
- phyB mutatione0
- Gene
- phyBe0
- Outcome
- early growth phenotypese0
- Direction
- suppressede0
- Comparator
- phyAe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the phyB mutation suppressed the early growth phenotypes of both phyA and cry1 seedlings”
e1“In Arabidopsis thaliana”
Claim · model-written summary
The phyB mutation suppressed early growth phenotypes of cry1 seedlings.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae1
- Treatment
- phyB mutatione0
- Gene
- phyBe0
- Outcome
- early growth phenotypese0
- Direction
- suppressede0
- Comparator
- cry1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the phyB mutation suppressed the early growth phenotypes of both phyA and cry1 seedlings”
e1“In Arabidopsis thaliana”
Claim · model-written summary
phyB appears to promote growth during the first 120 min of blue light, opposing cry1/phyA inhibition.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae1
- Gene
- phyBe0
- Outcome
- promoting growthe0
- Qualifier
- during at least the first 120 min of blue light treatmente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“phyB opposes the cry1/phyA-mediated inhibition by promoting growth during at least the first 120 min of blue light treatment”
e1“In Arabidopsis thaliana”
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